My ongoing 8.1 adventures...
01-06-2014, 02:05 AM
#65
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That looks evil
.. Looking at your graph in the previous post it shows the 202 and 203 kits withe the stock manifold. Is that an actual stock manifold or one of your ported ones? I'm tryin to decide on the 203 or 206 cam but I'm unsure what the difference is in the ported or factory intake?
Thanks
.. Looking at your graph in the previous post it shows the 202 and 203 kits withe the stock manifold. Is that an actual stock manifold or one of your ported ones? I'm tryin to decide on the 203 or 206 cam but I'm unsure what the difference is in the ported or factory intake?Thanks
The graph is a comparison of stock intake manifold with heads / 202 cam versus the Raylar Cool Gap manifold with heads / 202 cam. We added the 203 numbers to show how much the engine is starved by the stock manifold in performance applications.
You can actually make more torque and almost the same horsepower with the 202 heads/cam kit and ported manifold than the 203 heads/cam kit without manifold. Its that much of a restriction. The stock manifold chokes the engine, starving the motor past 4200rpm. If you're trying to pass smog, the ported manifold is the best solution. It flows about 70-80% of what the Cool Gap does and will produce roughly 70-80% of the gains.
The 203 camshaft is as large a camshaft as you can run with the stock heads and stock pistons. You will have to swap springs with the 203 (roller rockers will add another 18hp by reducing valve train friction). If you have our aluminum heads and forged dished pistons, then you can run the 206 camshaft which has a much higher lift. The 203 camshaft is an all-around street / strip camshaft for the 8.1L, whereas the 206 cam is great for maximum output.
Last edited by Raylar Engineering; 01-06-2014 at 02:14 AM.
01-06-2014, 10:15 PM
#67
Thank you, we're having fun with it. The suburban now moves like it weighs 2000lbs..
The graph is a comparison of stock intake manifold with heads / 202 cam versus the Raylar Cool Gap manifold with heads / 202 cam. We added the 203 numbers to show how much the engine is starved by the stock manifold in performance applications.
You can actually make more torque and almost the same horsepower with the 202 heads/cam kit and ported manifold than the 203 heads/cam kit without manifold. Its that much of a restriction. The stock manifold chokes the engine, starving the motor past 4200rpm. If you're trying to pass smog, the ported manifold is the best solution. It flows about 70-80% of what the Cool Gap does and will produce roughly 70-80% of the gains.
The 203 camshaft is as large a camshaft as you can run with the stock heads and stock pistons. You will have to swap springs with the 203 (roller rockers will add another 18hp by reducing valve train friction). If you have our aluminum heads and forged dished pistons, then you can run the 206 camshaft which has a much higher lift. The 203 camshaft is an all-around street / strip camshaft for the 8.1L, whereas the 206 cam is great for maximum output.
The graph is a comparison of stock intake manifold with heads / 202 cam versus the Raylar Cool Gap manifold with heads / 202 cam. We added the 203 numbers to show how much the engine is starved by the stock manifold in performance applications.
You can actually make more torque and almost the same horsepower with the 202 heads/cam kit and ported manifold than the 203 heads/cam kit without manifold. Its that much of a restriction. The stock manifold chokes the engine, starving the motor past 4200rpm. If you're trying to pass smog, the ported manifold is the best solution. It flows about 70-80% of what the Cool Gap does and will produce roughly 70-80% of the gains.
The 203 camshaft is as large a camshaft as you can run with the stock heads and stock pistons. You will have to swap springs with the 203 (roller rockers will add another 18hp by reducing valve train friction). If you have our aluminum heads and forged dished pistons, then you can run the 206 camshaft which has a much higher lift. The 203 camshaft is an all-around street / strip camshaft for the 8.1L, whereas the 206 cam is great for maximum output.
01-07-2014, 04:17 PM
#68
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Originally Posted by 02_2500avalanche
Did you guys happen to strap that thing to a dyno yet?
Raylar 540 Stroker Kit - Chevy Suburban 2500 - Vortec 8.1 Liter 496 - YouTube
Originally Posted by HemiHunter
I already have a set of your aluminum heads. The engine has roughly 80k on it. I figured I'd do the dished pistons when I get the heads on ( spring time). It's not a daily driver so I'm leanin toward the 206 cam. Thanks for all the help!!!
02-26-2014, 11:17 PM
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Finally strapped the 540 to a dyno. Brace yourself, mainline dynos read depressingly low.
For a baseline, we're using a previous 496 truck which came in with K&N / exhaust on the same dyno at 235rwhp/300rwtrq.
The 540 kit made 305rwhp/360rwtrq with K&N, the stock manifold, ported stock heads, roller rockers, 203 cam and JBA shorty headers. Assuming the previously mentioned semi-stock truck made the factory rated output (340hp/455trq) that means the 540 kit is making roughly 440hp / 540trq at the crank.
The stock injectors hit 100% duty cycle at 3900 RPMs on with this displacement and the lean condition is starting to affect power, so marine or larger injectors will be mandatory for the 540 kit. So running lean and restricted, a expect a gain of 70rwhp / 60rwtrq over stock. Our tuner demanded we bring the truck back as he expects another 10-20hp from the injector size increase.
As soon as we get the truck tuned with the larger injectors, the modified intake manifold and 80mm throttle body go on so we can see how much power is made with the modded manifold.
For a baseline, we're using a previous 496 truck which came in with K&N / exhaust on the same dyno at 235rwhp/300rwtrq.
The 540 kit made 305rwhp/360rwtrq with K&N, the stock manifold, ported stock heads, roller rockers, 203 cam and JBA shorty headers. Assuming the previously mentioned semi-stock truck made the factory rated output (340hp/455trq) that means the 540 kit is making roughly 440hp / 540trq at the crank.
The stock injectors hit 100% duty cycle at 3900 RPMs on with this displacement and the lean condition is starting to affect power, so marine or larger injectors will be mandatory for the 540 kit. So running lean and restricted, a expect a gain of 70rwhp / 60rwtrq over stock. Our tuner demanded we bring the truck back as he expects another 10-20hp from the injector size increase.
As soon as we get the truck tuned with the larger injectors, the modified intake manifold and 80mm throttle body go on so we can see how much power is made with the modded manifold.
Last edited by Raylar Engineering; 03-02-2014 at 10:14 PM.